The present invention is directed in general to an improved method and apparatus for carrying out minimally invasive treatments of the human body by virtual reality visualization of the treatment area. More particularly the invention is concerned with use of an apparatus and method for providing real time images of a human anatomy undergoing treatment along with rapid radiation seed therapy planning and rapid performance of therapy including an automatic seed loading methodology which enhances therapeutic treatment with greatly improved efficiency both in terms of time and resources.
New minimally invasive surgical procedures are most often optically guided, but such optical guidance methods do not permit visualization and guidance of instruments or probes within (inside) the target tissue or organ. Incorporation of real-time three-dimensional visualization inside diseased tissues would provide accurate guidance of therapy. Open-magnet MRI is used to visualize some procedures such as thermal therapy and brain biopsies. However, the method is expensive, not truly real-time, and is limited in application.
Numerous conventional treatment methods involve attempts to provide a targeted dosage of radiation or chemicals to the organ, and such treatments are often based on general anatomical assumptions of size and location. These methods suffer from inaccuracy of localizing the target for any one particular individual and potential real time changes of relative orientation and position of target tissue, normal tissue, and radiation therapy devices.
It is instructive in explaining the invention to consider one specific type of exemplary condition, adenocarcinoma of the male prostate which is the most commonly diagnosed cancer in the male population of the United States. At present, 254,000 new cases of prostate cancer were diagnosed in 1995 and 317,000 in 1996. In the 1960s, a method of implanting radioactive gold or iodine seeds was developed. With this approach, the radioactive material is permanently placed into the prostate via a retropubic approach during laparotomy when diagnostic lymphadenectomy was also being performed. A high dose of radiation is delivered to the prostate as the radioactive seeds decay. In several reports, the five year disease free survival (xe2x80x9clocal controlxe2x80x9d) obtained by this method was compared to similarly staged patients treated with an external radiation beam. In view of this, gold was replaced by I125 implantation for safety of personnel doing implantation. Except for early stage prostate cancer (T2 a tumors), inferior rates of local control are reported with xe2x80x9cfree handxe2x80x9d 125-Iodine implantation. There was significant dose inhomogeneity due to the nonuniformity of seed placement, leading to underdosing of portions of the prostate gland and significant complications due to overdosing of adjacent healthy tissue structures. The poor results for local control and normal tissue complication were attributed to the doctor""s inability to visualize and hence control where the radioactive seeds were actually being deposited inside the patient.
Recently, transrectal ultrasonography (xe2x80x9cTRUSxe2x80x9d) has been used to visualize 125-Iodine seed placement during transperineal implantation. The early reported rates of serious late complications is higher than external beam therapy. Even with this technique, significant imprecisions in seed placement are observed. Due to the proximity of the prostate to the rectum and bladder, incorrect seed placement may lead to serious overdosing of these structures and late complications.
The recent transrectal ultrasound guided transperineal implant technique has been developed which is in use. That procedure is described in three steps: (1) the initial volumetric assessment of the prostate gland performed using ultrasound, (2) development of a radiation therapy xe2x80x9cpre-plan,xe2x80x9d and (3) performing the actual intraoperative implant. The purpose of the initial volumetric assessment prior to the pre-plan or implantation is to obtain a quantitative understanding of the size of the prostate, which is then used to determine the total activity and distribution of radioactivity which is to be implanted into the prostate. To perform the assessment, an ultrasound probe is physically attached to a template. The template is a plastic rectangle which contains an array of holes separated at predefined intervals, usually 5 mm. The template system serves two purposes: (1) to fix the ultrasound probe, and hence the imaging plane to the reference frame of the catheter and seed positions, and (2) to guide the catheters into the prostate volume. More specifically, the template system serves as a reference frame for spatial quantities which are required for the description of the implant procedure. Using transrectal ultrasound, a number of serial ultrasound images are obtained at 5-mm intervals, and the prostate is outlined on each image. The images are taken so that the entire prostate gland is covered. This results in a stack of two-dimensional outlines, or contours, which, taken together, outline the entire three-dimensional prostate volume. From this volume, the quantitative volume of the prostate is calculated.
Once the three-dimensional contour data has been obtained for the prostate volume, a radiation therapy plan which describes the positions of the radioactive seeds within the prostate is developed. This plan attempts to optimize the dose to the prostate, minimize the dose to surrounding healthy tissue, and minimize dose inhomogeneity. The positions of the radioactive seeds are constrained to fall within the catheter tracks, since the seeds are placed within the prostate transperineally via these catheters. The result of the pre-plan describes the positions and strengths of the radioactive seeds within the catheter which optimizes the dose to the prostate.
Intraoperatively, the TRUS probe is inserted, and the template is mounted against the perineum. As previously described, the template is a plastic rectangle which contains an array of holes separated at fixed. intervals. These holes act as guides for the catheters. The TRUS probe is inserted into the rectum and placed so that the image corresponds to the prostate base (the maximum depth). Two or three catheters are inserted into the tissue surrounding the prostate or in the periphery of the prostate to immobilize the gland. These catheters contain no radioactive seeds. This image serves as a spatial reference for all further images and seed positions within the prostate. Subsequently, catheters are inserted into the gland based on the pre-plan through the template. The ultrasound probe is positioned each time so that the catheter, and hence seeds, which are inserted into the prostate are visible on the ultrasound image. If the placement of the catheter within the prostate is not according to the pre-plan, the catheter is then withdrawn and reinserted until the catheter is correctly placed. This is a time-consuming process; and it is very difficult to achieve optimal placement. Invariably, the catheters deflect angularly as they are inserted, and their positions are difficult to determine by two-dimensional ultrasound. This is due to the fact that the visualization process is a two-dimensional process while the actual implant procedure is three-dimensional. Once all the seeds are in place, another series of two-dimensional images are obtained to quantify the final, resultant dose distribution delivered to the patient. In some instances, a pair of orthogonal fluoroscopic images are also obtained to determine the final seed placements. This procedure is usually performed a few weeks post implant.
These above described prior art systems suffer from inherent inaccuracy, the inability to correct the positioning of the radioactive seeds without repeated withdrawal and reinsertion of seeds into the prostate and are not real time manipulations of the therapeutic medium. Further, the overall positioning of the template and patient may be different during treatment compared to the assessment phase. Consequently, the catheter position and seed position may be at an undesired position relative to the presumed assessment phase location.
It is therefore an object of the invention to provide an improved system and method for invasive treatment of the human body.
It is another object of the invention to provide a novel system and method for real time and/or near real time, three-dimensional visualization of a human organ undergoing invasive treatment.
It is also an object of the present invention to provide a more precise and accurate implant placement for radiation therapy, thermal therapy, and surgical ablation.
It is also an object of the invention to provide an improved system and method for generating a three-dimensional image data set of a human organ for a treatment protocol using a real-time ultrasound imaging system with spatial landmarks to relate the image data set to present time, invasive treatment devices.
It is a further object of the invention to provide a novel system and method for spatial registration of two-dimensional and three-dimensional images of a human organ, such as the human prostate, with the actual location of the organ in the body.
It is an additional object of the invention to provide an improved method and system for three-dimensional virtual imaging of the male prostate gland and overlaid virtual imaging of devices being inserted into the prostate for deposition of radioactive seeds for cancer therapy.
It is yet a further object of the invention to provide an automated method and system for loading of radioactive therapeutic treatment seeds based on a clinical plan enabling rapid treatment based on substantially real time pre-planning using rapid patient organ evaluation.
These and other objects and advantages of the invention will be readily apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings described below.